Obstructive sleep apnea is a common disorder that involves tissue occlusion of the nasopharyngeal airway during sleep which impedes a patient""s normal breathing cycle. Multiple sequential apnea episodes may result in severe sleep disruption of which the patient may not even be aware. Moreover, swollen tissue in the airway often results in excessive heavy snoring. Extreme sleep apnea is a serious disease which may affect as much as three percent of the adult population, and heavy snoring is much more common, particularly with overweight individuals.
Surgical intervention is always an option in alleviating obstructive sleep apnea or heavy snoring, however, most patients prefer to address the problem with non-invasive treatment. One treatment program involves the use of continuous positive airway pressure delivered to the patient""s airway to maintain the airway in a continuously open state during sleep. The equipment required to deliver continuous positive airway pressure to the airway of a patient includes a fan or blower for generating a pressurized flow through a hose coupled to a mask or nasal device which the patient places over his or her nose and uses straps about the head to fasten the device in place.
Many patients cannot tolerate the application of continuous positive airway pressure, particularly because of the discomfort associated with exhalation against a continuous positive pressure. An attempt has been made to alleviate this problem by the provision of a method and apparatus which provides a substantially constant elevated airway pressure to the patient""s airway, with periodic short term reductions of the elevated airway pressure to a pressure of lesser magnitude. A further advance in such treatment involves the application of alternative high- and low-level positive airway pressure wherein the low-level pressure coincides with the breath exhalation of the patient""s breathing cycle.
A method and apparatus for the application of continuous positive airway pressure to a patient""s airway is disclosed in U.S. Pat. No. 4,655,213, issued to Rapoport et al. The concept of providing a substantially constant elevated airway pressure with periodic short-term pressure reductions is disclosed in U.S. Pat. No. 4,773,411, issued to John B. Downs. A bi-level system of applying alternating high- and low-level positive airway pressure to a patient""s airway is disclosed in U.S. Pat. No. 5,148,802, issued to Sanders et al.
The methods and apparatus disclosed in the prior art for treating patients afflicted with such maladies as sleep apnea and snoring present a number of problems which need to be addressed. The equipment utilized in such treatment is far too bulky and cumbersome. The air stream delivered to the patient tends to dehydrate the nasopharyngeal tissue. The unnatural sensation and discomfort experienced by the patient in overcoming the positive pressure during breath exhalation results in many patients abandoning the use of a system that is in all other respects quite beneficial.
The present invention comprehends the treatment of such disorders as obstructive sleep apnea or heavy snoring by providing apparatus capable of delivering a pressurized burst or pulse of air to a patient""s nasopharyngeal airway at the moment of termination of the patient""s breath exhalation during the breathing cycle. The pulse of pressurized airflow is sufficient to prevent the development of airway tissue occlusion and maintain the airway open for normal breathing.
Hence, it is a primary objective of the present invention to provide a method of alleviating sleep apnea or snoring by delivering ambient air to a patient""s airway in the form of an air bolus, wherein the patient""s exhaled air is utilized to actuate an energy storing means to cause delivery of the air bolus into the airway.
Still another objective of the present invention is to provide apparatus capable of providing a pressurized pulse of air through a nasal device and into the nasopharyngeal airway of a sleeping patient, wherein the pressurized airflow is triggered by the breath exhalation of the patient and will continue sequentially with each exhaled breath.
It is also an objective of the present invention to provide apparatus as heretofore described which preferably includes a nasal device for attachment to a patient""s nose, and a housing with a chamber capable of storing a fresh air supply for release to the nasal device and into the patient""s airway to thus promote a normal breathing cycle.
It is also an objective of the present invention to provide apparatus as heretofore described which is self-contained as a unitized structure that obviates the need for auxiliary remote bedside equipment requiring a large fan or compressor.
Practice of the method of this invention comprises the steps of providing a primary airflow conduit for delivering ambient air into the patient""s airway and providing a bolus chamber in airflow connection with the airflow conduit which is capable of delivering a bolus of ambient air. Energy storing means responsive to the patient""s breath exhalation is utilized to force the bolus of air from the chamber and through the conduit and into the patient""s airway. The patient""s exhaled air is used to actuate or trigger the energy storing means and cause, by the release of its energy, the delivery of the bolus of air to the patient""s airway.
The invention also provides apparatus in the form of a unitary structure, such as a containment housing, with the housing being coupled to a nasal device. The nasal device may be a mask sealed to the patient""s face and about the nose or a device comprising a pair of nasal delivery members, such as disclosed in U.S. Pat. No. 5,687,715, issued to Landis et al. The containment housing of the apparatus includes a first chamber for receiving breath exhaled by the patient and a second chamber for storing fresh air for delivery back to the patient at a predetermined time during the patient""s breathing cycle. The chambers are expandable and operatively interconnected whereby expansion of the first chamber causes expansion of the second chamber. An energy storing means is provided within the containment housing which is adapted to operate, at the moment of completion of the patient""s breath exhalation, to contract both of the expandable chambers and cause a momentary burst of pressurized airflow to be ejected from the second chamber and through the nasal device to the patient""s airway. The pressurized airflow is only momentary, whereby completion of air inhalation occurs naturally and voluntarily by the patient.